論文 - 山野井　一人

Thickness dependence of spin wave nonreciprocity in permalloy film

Masaki Nakayama, Kazuto Yamanoi, Shinya Kasai, Seiji Mitani, Takashi Manago

Japanese Journal of Applied Physics （IOP PUBLISHING LTD）  54 （ 8 ）  2015年08月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  0021-4922

　概要を見る

The amplitude of the spin wave (magnetostatic surface spin wave) depends on the propagation direction. Nonreciprocity hardly depends on the permalloy (Py) thickness between 100 and 300 nm, and it is determined by the spin wave resonant frequency. The nonreciprocal parameter decreases with increasing frequency, resulting in the large amplitude asymmetry at high frequencies, which is well supported by a result of theoretical analysis. The nonreciprocity of a 25-nm-thick-film, however, is lower than those of thicker films. This is qualitatively explained by a schematic model based on the origin of nonreciprocity.

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Damping factor estimation using spin wave attenuation in permalloy film

Takashi Manago, Kazuto Yamanoi, Shinya Kasai, Seiji Mitani

Journal of Applied Physics （AMER INST PHYSICS）  117 （ 17 ）  2015年05月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  0021-8979

　概要を見る

Damping factor of a Permalloy (Py) thin film is estimated by using the magnetostatic spin wave propagation. The attenuation lengths are obtained by the dependence of the transmission intensity on the antenna distance, and decrease with increasing magnetic fields. The relationship between the attenuation length, damping factor, and external magnetic field is derived theoretically, and the damping factor was determined to be 0.0063 by fitting the magnetic field dependence of the attenuation length, using the derived equation. The obtained value is in good agreement with the general value of Py. Thus, this estimation method of the damping factor using spin waves attenuation can be useful tool for ferromagnetic thin films.

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Measurement of the ferromagnetic resonance of a single micron dot by using a vector network analyzer

Kazuto Yamanoi, Takashi Manago, Satoshi Yakata, Takashi Kimura

Journal of the Korean Physical Society （KOREAN PHYSICAL SOC）  63 （ 3 ） 800 - 803 2013年08月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り,  ISSN  0374-4884

　概要を見る

The ferromagnetic resonance of a single micron-scale dot of permalloy was measured by using a vector network analyzer. The resonant frequency shifted to higher frequency with increasing aspect ratio of the sample. This tendency was remarkable for narrower width samples, especially the 1-μm-width dots. This means that the demagnetization effect of thin films for the ferromagnetic resonance becomes large when the sample width is less than 1 μm. The resonant frequency can be largely controlled by changing the sample width for a thin film with a width of less than 1 μm, which is a favorable characteristics for various microwave applications. © 2013 The Korean Physical Society.

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Spin wave excitation and propagation properties in a permalloy film

Kazuto Yamanoi, Satoshi Yakata, Takashi Kimura, Takashi Manago

Japanese Journal of Applied Physics （IOP PUBLISHING LTD）  52 （ 8 ）  2013年08月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り,  ISSN  0021-4922

　概要を見る

Spin wave excitation and propagation properties in a permalloy were investigated using a vector network analyzer for the magnetostatic surface wave (MSSW) and magnetostatic backward volume wave (MSBVW) configurations. In the MSSW configuration, the excitation and transmission spectra show many peaks. They originate at the distance of antenna lines of the coplanar waveguide, and the waveguide design is important for selecting the excitation and transmission wave vectors of the spin wave. The attenuation length of the MSSW was estimated to be 7.1 μm, and the group velocity of the MSSW with a wave number of 0.26 μm-1 was estimated to be about 8.6 μm/ns for an external magnetic field of 20 mT. In the MSBVW configuration, however, the excitation spin wave spectrum shows a single peak, since many quantized peaks overlap. A transmission signal with a single peak was also detected, but this could be an artifact such as an induced current. © 2013 The Japan Society of Applied Physics.

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Size dependence of ferromagnetic resonance frequency in submicron patterned magnet

Takashi Manago, Kazuto Yamanoi, Satoshi Yakata, Takashi Kimura

Japanese Journal of Applied Physics （IOP PUBLISHING LTD）  52 （ 5 ）  2013年05月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  0021-4922

　概要を見る

We investigated the size effect on ferromagnetic resonance (FMR) in a submicron-wide single permalloy bar. The resonant frequency markedly increased with decreasing bar width to less than 1 m, since the demagnetizing field is effectively modified by changing the bar width even in thin films. The resonant frequency difference between 100- and 1000-nm-wide bars was over 4 GHz in the absence of a magnetic field. This characteristic is promising for practical microwave devices because the desired resonant frequency can be obtained simply by varying the width of narrow ferromagnetic bars so that it is not necessary to change the material or magnetic field. © 2013 The Japan Society of Applied Physics.

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